It is difficult to measure the physical properties of a fluid in a potential petroleum bearing rock formation. The use of a logging method to measure mobility (permeability divided by viscosity) typically requires measuring of a fluid flow rate simultaneously with a pressure gradient. These measurements may be difficult to do especially in downhole applications.
Typical penetration depths for petroleum bearing rock formation may range from about 0.1 mm to about 20 cm, more particularly about 1 mm to about 10 cm, e.g., for a rock formation saturated with water-like fluids. The methods, systems and devices may be used in downhole applications, or in situations where a core sample is taken, the core sample may be brought uphole and analyzed using the methods, systems and devices disclosed herein on or off-site, e.g., in a laboratory using an electromagnet or superconducting NMR.
There are many drawbacks of existing techniques of measuring physical properties of porous media such as, for example, a potential petroleum bearing rock formation. For example, mudcake barriers may cause unknown effects and give aberrant results. Leakage around probes or unknown effects of empirically based correlations, e.g., NMR decay rate measurements, estimates based on mineralogy, can provide inaccurate results. Such problems make physical property measurements, such as mobility, of a potential petroleum bearing rock formation difficult to accomplish, particularly using a logging method.
It is an object of the present invention to address these difficulties.